THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 

LOS  ANGELES 

GIFT  OF 

U.  of  Calif. 
Berkeley 


MODERN  STEAM  TURBINES 

BRITISH   AND  FOREIGN. 


COMPRISING  DESCRIPTIONS  OF  SOME 
TYPICAL  SYSTEMS  OF  CONSTRUCTION. 


UNDER    THE    EDITORSHIP    OF 

ARTHUR    R.    LIDDELL, 

Vol.  I. 
THE  SCHULZ  STEAM  TURBINE. 


MODERN   STEAM  TURBINES. 


VOL.  I. 
THE   SCHULZ   STEAM  TURBINE. 


THE 


SCHULZ  STEAM  TURBINE 


FOR 

LAND  AND  MARINE  PURPOSES 

With  special   reference  to  its  application  to  War  Vessels, 
BY 

MAX    DIETRICH, 

Marine-Oberingenieur  A.D.  of  the  German  Navy, 

With   43   illustrations   and   diagrams,   and   6   tables. 


NEW     YORK 

E.  P.  DUTTON  AND  COMPANY 

31    WEST    TWENTY-THIRD    STREET 
1907 


ALL    RIGHTS    RESERVED. 


&iein«riiig 
Libr.r, 

TJ 


PREFACE. 


The  growing  importance  of  the  steam  turbine  for  land 
purposes,  and  still  more  for  the  propulsion  of  ships,  has  prompted 
us  to  bring  some  of  the  results  of  British  and  foreign  endeavours 
in  this  field  within  the  reach  of  interested  parties. 

The  volumes  of  this  series  comprise  descriptions  of  some  of 
the  systems  of  which  encouraging  practical  trial  has  been  made,  or 
which,  in  view  of  the  past  record  of  their  authors,  have  a  prima 
facie  claim  to  be  taken  seriously  as  engineering  probabilities  of  the 
future. 

It  is  clear  that  a  new  departure  in  practical  engineering 
must  present  for  solution  many  new  problems,  each  of  which  may 
be  approached  in  a  variety  of  ways,  and  a  knowledge  of  the  successes 
and  failures  of  other  designers  who  have  made  practical  trial  of  this 
or  that  expedient  will  doubtless  supply  hints  in  many  directions. 
Even  untried  proposals  may  point  the  way  to  solutions  of  difficult 
questions,  whether  of  principle  or  of  detail. 

In  regard  to  matters  of  controversy  between  rival  inventors, 
which  show  themselves  in  some  of  the  works  in  the  collection,  it 
is  not  the  intention  to  take  sides  between  different  engineers  or 
different  schools  of  engineering,  nor  to  show  preference  in  any 
direction,  but  simply  to  lay  ex  parte  statements  before  our  readers 


733411 


with  all  impartiality,  in  the  hope  that  mutual  understanding  and 
appreciation  may  thereby  be  promoted,  and  that  the  advantages  of 
different  systems  may,  in  course  of  time,  be  combined  in  one  good 
standard  type  of  engine. 

It  is  hoped  that  the  publication  of  the  present  series  may 
prove  a  timely  one  and  may  bring  advantage  to  the  engineering 
profession. 


AKTHUB  E,   LIDDELL. 

August,  1906. 


This  volume  is  an  authorised  translation  of  "Die  Dampfturbine  von  Scbnlz,"  by 
Max  Dietrich,  published  by  C.  J.  E.  Volckmann,  of  Rostock,  German     1906. 


THE    SCHULZ    STEAM    TURBINES. 


These  turbines  are  not  only  for  land  purposes,  such  as  that  of 
supplying  the  motive  power  for  light  and  power  installations  and 
locomotives,  but  are  also  especially  adapted  for  marine  work,  such  as 
the  driving  of  the  screw  propeller. 

Richard  Schulz,  the  designer  of  these  turbines,  as  Engine- 
works  Manager  of  the  Germania  Shipyard  of  Friedrich  Krupp  in 
Kiel,  has  had  many  years  of  experience  in  the  construction  of  engines 
for  use  on  land,  and  still  more  in  that  of  marine  engines.  He  has, 
therefore,  had  ample  opportunity  of  studying  the  conditions  which 
such  turbines  must  fulfil,  if  they  are  to  enter  into  successful  com- 
petition with  the  ordinary  reciprocating  engine.  Since  in  the  Ger- 
mania Shipyard  at  Kiel  not  only  large  torpedo  boats,  but  the  very 
largest  ships  of  the  German  Navy  are  built,  Herr  Schulz  has  been 
obliged  to  consider  the  suitability  of  the  turbine  for  warships  of  every 
possible  kind. 

The  patents  published  hitherto  and  the  designs  embodied  in 
them  show  that  both  the  action  and  the  reaction  principles  have  had 
application,  and  have  been  developed  as  independently  as  possible. 
Turbines  on  the  action  principle  with  expansion  stages,  in  which 
each  of  the  working-wheels  runs  in  a  separate  chamber  the  walls 
of  which  support  the  guide  blades,  have  been  known  for  more  than 
thirty  years  (See  "Roues  et  turbines  a  rapeur,"  by  K.  Sosnowsky, 
Paris).  The  steam  turbines  of  Bateau,  Zoelly,  Curtis,  &c.,  are 
newer  constructions  on  the  same  principle ;  but  no  types  hitherto 
known  make  complete  use  of  the  available  motive  power — in  this 
case  the  steam — ichen  the  work  to  be  done  is  small. 


8 

To  alter  the  output,  Zoelly  simply  throttled  the  steam. 
Ratcau  sometimes,  and  Curtis  probably  always,  employed  as  con- 
stant an  initial  pressure  as  possible,  but  devised  no  means  of  regu- 
lating the  pressure  in  the  subsequent  expansion  stages.  Conse- 
quently, they  failed  to  make  full  use  of  the  steam  energy,  especially 
when  the  output  was  inconsiderable. 

In  the  new  Schulz  turbines,  on  the  other  hand,  not  only  the 
initial  pressure,  but  the  pressure  in  every  expansion  stage  is  so  regu- 
lated, either  by  hand  or  by  some  automatic  device,  that  full  use  can 
be  made  of  the  steam,  even  for  a  minimum  of  work. 

The  principal  patent  in  this  connection  is  the  "Regulating 
apparatus  for  multi-stage  expansion  turbines,"  No.  132,868;  class 
14c,  of  March  26th,  1901.  This  and  the  patents  mentioned  in  the 
specification  refer  to 

(a)  Several  expansion  stages,  as  in  the  designs  of  Rateau, 
Zoelly,  &c. 

(b)  Several  expansion  stages  with  subsidiary  speed-expan- 
sions, as  in  those  of  Curtis,  Riedler,  Stumpf,  &c. 

The  new  action  turbine,  of  Schulz  (Fig.  14)  is  devised  chiefly 
for  use  on  land.  It  has  from  one  to  ten  or  even  more  expansion 
stages,  each  of  which  can  be  amplified  by  one  or  several  subsidiary 
speed  stages.  In  every  detail  of  its  construction  this  turbine  shows 
the  requisite  simplicity  and  strength.  Between  the  fixed  and  the 
rotating  portions  are  clearance  spaces  of  from  £  to  \  of  an  inch.  This 
ensures  safe  working. 

A  special  valve  or  ring  slide  regulates  the  work  done  in  each 
expansion  stage,  so  that  the  available  boiler  pressure  is  used  to  the 
best  advantage,  whatever  may  be  the  output. 

This  condition  is  fulfilled  likewise  by  the  Laval  turbine ;  for 
in  it,  whether  the  work  done  be  little  or  much,  the  pressure  and 
change  of  temperature  of  the  steam  are  utilized  as  completely  and 
evenly  as  possible. 


9 

Schulz'  action  turbines  can  be  used  both  for  the  smallest  out- 
puts of  2  or  3  horse-power  and  for  the  highest  up  to  15,000  horse- 
power or  more.  Moreover,  both  high  and  low  peripheral  velocities 
down  even  to  65  feet  a  second  or  less  can  be  obtained.  The  number 
of  expansion  stages,  and  especially  also  that  of  the  subsidiary  speed 
stages,  depends  on  the  required  peripheral  velocity.  The  shaft 
may  be  placed  either  vertically  or  horizontally. 

Schulz'  reaction  turbine  differs  from  the  well-known  Parson's 
turbine  principally  in  the  fact  that  the  end  thrust  unavoidable  in  this 
sort  of  turbine  is  nullified  without  the  employment  of  a  grooved 
"labyrinth  piston."  Schulz  has  solved  the  problem  in  many 
different  ways ;  the  contrivances  for  this  purpose  are  described  in 
detail  further  on. 

This  reaction  turbine  is  remarkable  for  its  strength  and  for 
the  ease  with  which  it  can  be  constructed.  Its  length  is  less  than 
that  of  turbines  of  other  systems;  and  since  in  spite  of  this  the  steam 
is  utilized  satisfactorily,  this  turbine  is  powerful  in  proportion  to  its 
size  and  weight  (See  the  comparison  between  the  various  turbines  in 
Figs.  39  to  43).  It  can  be  employed  for  outputs  of  from  50  to 
15,000  horse-power,  or  even  more. 

Superheating  is  considered  an  advantage  in  both  kinds  of 
turbine. 


The  first  problem  attacked  by  Schulz  was  to  make  turbines 
reversible,  that  is,  to  enable  them  to  drive  ships  either  forwards  or 
backwards.  He  laid  the  greatest  stress  on  this  point  in  his  first 
designs,  which  go  back  as  far  as  the  year  1897.  Only  in  his  later 
plans  did  he  pay  increased  attention  to  the  other  properties  which 
should  be  possessed  by  an  engine  for  use  on  land  or  sea.  The  most 
important  of  these  is  that  the  turbine  should  be  economical,  not  only 


10 

when  its  output  is  large,  but  also  when  the  work  done  is  moderate 
or  little. 

For  a  marine  engine,  economy  in  the  use  of  steam  is  usually 
demanded  only  for  motion  ahead.  When  the  engines  are  reversed , 
a  rapid  answer  of  the  ship  to  the  rotation  of  the  propeller  is  of  more 
importance. 

The  engines  of  warships  or  merchant  vessels  are  reversed 
when  the  ship  is  manoeuvring  or  is  going  in  or  out  of  a  port,  and 
when  the  danger  of  a  collision  or  some  similar  unforeseen  circum- 
stance arises.  In  these  cases  an  economical  use  of  the  steam  is- 
generally  not  necessary,  for  when  the  engines  are  worked  irregularly, 
we  cannot  regulate  the  generation  of  steam  in  the  boilers  so  that  the 
pressure  is  no  greater  than  the  needs  of  the  moment  require.  In 
most  cases  superfluous  steam  is  formed,  which  must  be  carried  off 
to  the  condenser  to  avoid  waste  of  fresh  water. 

One  simple  means  of  obtaining  a  reversible  turbine  system  is- 
to  place  two  equal  turbines  on  a  common  shaft,  one  for  motion  ahead 
and  the  other  for  motion  astern.  The  weight  and  space  require- 
ments of  this  system  are,  however,  so  great  as  to  render  it  unsuitable 
for  a  marine  engine.  The  designers  of  steam  turbines  have  often 
supposed  that  they  could  avoid  this  difficulty  by  using  a  large  turbine 
for  motion  ahead  and  a  small  one  for  motion  astern.  Experiments 
on  such  systems  have,  however,  shown  that  they  are,  at  any  rate, 
inapplicable  to  men  of  war. 

The  disadvantages  of  a  go-astern  engine  of  small  output  are 
not  so  noticeable  in  smaller  vessels,  such  as  tugs  or  torpedo  boats, 
but  in  larger  ships  they  are  very  much  in  evidence.  In  such  cases 
the  hull  answers  to  the  propeller  much  too  slowly,  and  it  is  a  long 
time  before  the  ship  begins  to  move  in  the  direction  opposite  to  that 
in  which  she  had  previously  been  going,  perhaps  at  a  high  speed. 
This  drawback  is  exaggerated  by  the  fact  that  a  turbine  engine 
is  obliged  to  have  a  comparatively  small  screw. 

If,  however,  vessels  of  any  sort  manoeuvre  indifferently,  they 


11 

are  in  frequent  danger  of  collision,  while  men  of  war  lose  their  value 
as  fighting  units. 

We  draw  the  following  conclusions  as  to  the  conditions  which 
should  be  satisfied  by  a  marine  turbine.  For  motion  ahead  it  must 
make  full  use  of  the  available  energy,  so  as  to  economise  coal.  For 
motion  astern  this  is  of  less  importance,  but  the  turbine  should  be  of 
a  size  sufficient  to  affect  the  ship's  motion  promptly  and  effectively. 

Schulz  has  made  a  number  of  designs  to  satisfy  these  con- 
ditions, and  has  protected  them  by  patents  in  Germany  and  else- 
where. In  these  the  chief  consideration  has  been  to  make  the  go- 
astern  turbine  as  powerful  as  possible  without  its  at  the  same  time 
being  unreasonably  extravagant  in  the  use  of  steam.  Although  in 
manoeuvring  a  large  quantity  of  steam  must  be  at  our  disposal,  and 
often  some  of  it  must  be  led  away  into  the  condenser  or  into  the  open 
air,  yet  occasionally  this  superfluous  steam  is  not  available,  as  for 
instance,  when  the  engines  are  reversed  for  several  minutes  at  a 
time.  It  follows  that  a  go-astern  turbine  should  not  use  more  steam 
than  would  have  been  required  during  the  time  in  which  it  acted  for 
motion  ahead. 

It  is  convenient  to  enclose  the  go-ahead  and  go-astern  tur- 
bines in  a  single  case.  Parsons  also  recognised  this  fact,  and  a  year 
later  than  Schulz  he  took  out  a  patent  for  a  go-astern  reversing  tur- 
bine placed  abaft  of  the  go-ahead  engine.  He  thereby  economised 
weight  and  space,  but  the  reversing  turbine  had  too  small  an  output 
and  was  not  sufficiently  accessible  for  inspection  and  repairs. 

The  two  first  Schulz  turbines  (Figs.  1  and  18)  were  turned  out 
from  the  Engineering  Works  of  the  Germania  Shipyard  at  Tegel, 
near  Berlin,  in  the  years  1898  and  1900.  The  improvements  which 
time  has  brought  wrere  partly  tested  on  these  experimental  turbines. 

In  1901  the  second  of  the  turbines  represented  in  Figs.  18  and 
19  was,  immediately  after  completion,  placed  in  a  boat  of  19  tons 
displacement  and  performed  all  its  manoeuvres  without  a  hitch.  A 
description  of  these  turbines  is  given  further  on. 


12 


The  first  turbines  designed  by  Schulz  are  shown  in  Figs.  1 
and  2.  They  were  patented  in  April,  1898,  as  "Compound  turbines" 
(No.  103,879;  Class  14).  Many  experiments  on  the  driving  of 
screws  and  dynamos  were  made  in  1899  with  the  radial  turbine  of 
Fig.  1.  Some  results  of  these  tests  are  given  in  Table  I.  The 
maximum  output  was  51  electric  horse-power,  when  the  number  of 
revolutions  was  1,700  per  minute  and  the  boiler  pressure  was 
2051bs.  per  square  inch. 


Fig.  i. 


In  the  case  G  are  one  or  more  working  wheels  fastened  to  the 
shaft  /.  These  carry  on  their  sides  the  working-wheel  blades  ar- 
ranged in  concentric  rinjjs.  Attached  to  the  case  are  the  fixed 


13 

blades  g,  also  concentrically  arranged,  which  guide  the  steam  in  the 
necessary  direction  to  the  working-wheel  blades.  Part  T  of  the 
working-wheel  drives  forwards  :  the  other  part,  T',  backwards.  The 
entry  of  the  steam  is  regulated  by  a  three-way  valve.  The  tube  V 
leading  from  this  opens  into  the  steam  chest  a  and  enables  the  steam 
to  drive  forwards.  The  steam  finds  its  way  to  the  ring  of  blades  br 
lying  next  to  the  shaft  /,  and  after  going  through  the  other  rings  in 
order,  finally  passes  through  the  outermost  ring  c  and  leaves  the 
case  at  d.  Thence  it  passes  into  the  condenser  or  to  the  open  air. 
The  tube  R,  also  leading  from  the  three-way  valve,  opens  into  the 
two  steam  chests  e,  and  enables  the  steam  to  drive  backwards.  ID 


Fig.  2. 


this  case  also  the  steam  passes  first  through  the  blades  nearest  the 
shaft  and  finally,  after  its  energy  has  been  exhausted,  leaves  the  case 
at  d,  as  before. 

The  end  thrust  is  eliminated  by  the  arrangement  of  two  equal 
turbines  with  the  common  steam  supply  for  motion  ahead  arranged 
between  them  and  with  separate  supplies  for  motion  astern  arranged 
at  their  outer  sides.  One  of  the  oldest  of  Schulz'  patents,  viz.,  the 
engine  illustrated  in  Fig.  2,  may  here  appropriately  take  its  place. 


14 

It  is  composed  of  a  go-head  turbine  with  axial  flow  and  a  go- 
astern  radial  turbine.  The  working-wheel  here  takes  the  form  of  a 
•drum  shaped  like  a  truncated  cone.  The  two  ends  of  this  cone 
are  closed  by  the  plates  i  and  i  ,  which  serve  as  bearings  for  the  shaft 
J.  The  case  g,  which  supports  the  fixed  blades,  fits  the  shape  of  the 
working  parts.  The  rings  of  working- wheel  blades  (b  to  c),  which 
drive  forwards,  are  fixed  on  the  sloping  sides  of  the  working  drum. 
Those  which  drive  backwards  are  placed  on  the  base  of  the  drum. 
The  design  and  arrangement  of  the  steam  supply  may  be  seen  in 
the  figure.  The  rings  of  blades  for  motion  astern  are  of  as  large  a 
•diameter  and  are  situated  as  near  the  steam  exit  d  as  possible,  so  that 
they  may  offer  no  resistance  while  the  engine  is  driving  ahead. 


A  disadvantage  of  reaction  turbines  is  the  end  thrust  with 
which  the  steam  acts  on  the  working- wheel.  In  large  turbines  this 
may  reach  very  considerable  values.  Parsons  eliminates  this  thrust 
by  the  use  of  counteracting  pistons,  forming  the  well-known  "laby- 
rinth apparatus." 

These  increase  the  length  of  the  turbine  and  consequently 
waste  space  ;  moreover  they  are  extravagant  in  steam.  Economy  of 
space  is,  however,  one  of  the  chief  aims  of  modern  builders  of  every 
kind  of  engine,  and  loss  of  steam  (though  this  is  less  important) 
.should  also  be  avoided. 

The  use  of  reaction  turbines  as  marine  engines  necessitates 
the  employment  of  a  large  number  of  fixed  and  revolving  blades,  if 
the  peripheral  velocity  is  to  be  sufficiently  low.  Marine  turbines 
must,  therefore,  have  comparatively  many  more  rings  of  blades  than 
stationary  engines.  It  is  necessary,  especially  for  marine  purposes, 


15 

that  these  numerous  blade  rings  should  be  divided  among  several 
drums,  so  that  the  shaft  may,  by  reason  of  the  shortness  of  the  indivi- 
dual drums,  be  more  firmly  and  securely  mounted.  Schulz'  designs 
satisfy  this  condition  adequately  and  at  the  same  time  eliminate  the 
end  thrust. 

Schuh  patented  a  compound  steam  turbine  in  November, 
1900  (No.  137,792;  Class  14C),  in  which  two  turbines  are  symmetri- 
cally arranged  with  their  end  thrusts  acting  in  opposite  directions. 
A  number  of  rotating  blades  are  fastened  on  two  drums  of  different 
diameters.  By  means  of  a  suitable  flow  of  steam  the  end  thrusts  of 
these  drums  are  opposed  in  such  a  manner  that  the  pressure  on  the 
thrust  block  is  entirely  eliminated,  or  at  least  brought  within  reason- 
able limits. 

Fig.  3  shows  a  compound  turbine  of  this  kind,  in  which  the 
diameters  of  the  rings  of  fixed  and  revolving  blades  (as  in  Fig.  2) 


increase  in  the  direction  of  flow  of  the  steam.  Jn  the  patent,  how- 
ever, provision  is  also  made  for  the  case  in  which  the  rings  of  the 
high  and  low  pressure  turbines  respectively  are  of  equal  diameter. 

In  Fig.  3  the  high-pressure  turbine  with  the  smaller  blade 
rings  is  denoted  by  the  letter  a,  the  low  pressure  turbine  with  larger 
rings  by  6.  Both  revolving  drums  are  enclosed  in  a  common  case  d 


16 

and  are  fixed  to  the  shaft  c.  The  steam  enters  the  turbine  at  e,  and 
after  passing  through  the  fixed  and  revolving  blades  of  the  high 
pressure  engine,  is  regulated  by  the  valve  g.  Tt  then  goes  through 
the  connecting  pipe  /  arid  the  tube  It,  finds  its  way  at  h  into  the  low 
pressure  turbine,  and  is  led  away  at  i  into  the  condenser  or  into  the 
open  air.  In  a  and  b  the  steam  flows  in  opposite  directions. 

The  fixed  blades  in  a  and  b  are  placed  in  such  a  way  that  both 
a  and  b  drive  in  the  same  direction.  The  valve  g  at  the  mouth  of  the 
pipe  /  regulates  the  pressure  of  the  steam  as  it  leaves  a.  In  this  way 
the  resultant  end  thrust  on  the  thrust  block  n  can  be  altered  within 
certain  limits. 

As  in  Fig.  2,  the  moveable  reversing  blades  are  fastened  to  the 
base  of  the  low-pressure  working  drum  and  the  fixed  blades  to  the 
corresponding  cover  of  the  case.  The  steam  for  reversing  enters 
through  the  pipe  m ,  and  in  this  case  also  reaches  the  smallest  of  the 
concentric  rings  of  fixed  blades  first.  The  steam,  as  in  the  case  of 
direct  rotation,  leaves  at  i,  close  to  the  outermost  ring. 

This  radial  go-astern  turbine  can  also  be  replaced  by  a  shorter 
axial  engine,  as  is  shown  in  a  diagram  in  the  patent  specification. 

Compound  turbines  are  composed  of  two  or  more  turbine- 
drums,  whose  rotating  parts  are  placed  in  separate  cases,  and  sit 
either  on  a  single  shaft  or  on  several  distinct  shafts.  Of  the  many 
combinations  which  are  given  in  the  before-mentioned  patent  No. 
137, v 02,  v\e  shall  mention  only  two. 

Fig.  4  shows  four  turbine-drums  a,  b,  u,  v,  placed  on  a  single 
shaft.  The  arrows  show  the  direction  of  the  driving  steam  and 


Fig.   4. 


17 

hence  the  directions  of  the  corresponding  end  thrusts.  We  see  that 
a,b,  and  u  give  an  end  thrust  to  the  shaft  in  a  direction  opposite  to 
that  given  by  v. 

In  Fig.  5  the  drums  are  divided  between  two  shafts.  Here 
we  see  an  arrangement  in  which  the  smaller  turbines  a  and  b  act  on 
one  shaft,  the  larger  ones«  and  v  on  the  other.  The  distribution  of 
the  steam  flow  necessary  to  counteract  end  thrust  is  clear  from  the 
figure. 


In  this  diagram  only  the  grouping  of  the  four  drums  is  new. 
Monsieur  Tournaire  (as  is  well  known)  had  as  early  as  1853  described 
in  detail  a  method  in  which  several  turbines,  worked  one  after  another 
by  a  flow  of  steam,  can  be  made  to  drive  several  shafts  simultaneously. 

In  stationary  turbines  the  end  thrust  should,  of  course,  be 
abolished  as  completely  as  possible.  In  marine  engines,  on  the 
other  hand,  the  end  thrust  should  be  adjusted  by  a  suitable  choice  oi 
the  diameter  of  the  revolving  parts,  so  as  just  to  counterbalance  the 
thrust  of  the  screw.  When  the  ship  is  going  ahead,  this  screw  thrust 
is  towards  the  bow,  so  that  the  turbine  thrust  should  be  of  equal 
amount,  but  should  act  in  the  direction  of  the  stern. 


18 

For  better  regulation  of  the  axial  thrust  the  use  of  manometers 
on  suitable  parts  of  the  high  and  low  pressure  engine  cases  is  advan- 
tageous. When  the  pressures  of  the  steam  in  the  two  turbines  are 
known,  the  end  thrust  may  be  determined.  The  difference  of  pres- 
sure and  hence  the  thrust  may  be  altered  to  some  small  extent  by  the 
valve  g  (Fig.  3). 


Another  design  patented  in  July  1901,  (No.  135,937;  Class 
14c)  also  aims  at  the  abolition  of  end  thrust.  Two  such  turbines  are 
represented  in  Figs.  6  and  7. 

Fig.  6  shows  a  longitudinal  section  of  a  turbine  rotating  in  a 
single  direction  only.  It  is  admirably  suited  for  use  011  land.  The 
flow  is  partly  radial  and  partly  axial.  The  axial  portion  of  the 
rotating  parts  is  denoted  by  a,  and  the  radial  by  6.  The  case  e  is 


Fig.  6. 


19 

closed  by  the  covers  x  and  y.  The  radial  portion  of  the  revolving 
blades  is  placed  in  a  ring-shaped  extension  of  the  case,  and  here  also 
is  the  steam  chest  z  for  the  entering  steam.  The  cover  y  carries  the 
chest  /,  through  which  the  steam  exhausts.  The  direction  of  flow  of 
ihe  steam  is  shown  by  arrows. 

Fig.  7  shows  a  section   through  a  turbine  with   radial   and 
.axial   flow,   which   is   reversible.      For   direct   motion   this   turbine 


Fig.  7. 


"has  two  axial  drums,  a  larger  and  a  smaller,  denoted  by  1  and  2 
respectively.  The  rotating  apparatus  a  6  for  reversing  is,  a,s  in 
Fig.  6,  partly  axial  and  partly  radial. 

In  the  turbine  of  Fig.  6,  and  in  the  reversing  portion  of  Fig.  7, 
the  steam  is  divided  on  its  entrance  into  the  case  and  passes  at  the  same 
lime  through  the  radial  (6)  and  the  axial  (a)  parts  of  the  common 


20 

rotation  rings.  Both  a  and  b  give  an  end  thrust  towards  the  right , 
but  the  steam  flowing  against  the  back  of  the  flange-like  part  b  before 
its  entrance  into  a,  gives  a  thrust  towards  the  left.  This  latter  may 
be  regulated  at  pleasure — so,  for  instance,  as  exactly  to  counter- 
balance the  thrust  to  the  right. 

In  eliminating  the  end  thrust,  the  chief  consideration  is,  in 
the  go-ahead  turbine,  the  difference  of  pressure  in  1  and  2 — in  the 
reversing  turbine  the  breadth  of  the  flange  placed  on  the  drum  wall 
of  b. 


After  solving  the  problem  of  the  design  of  a  turbine  which 
should  fulfil  the  necessary  conditions  of  ease  of  reversal  and  elimina- 
tion of  end  thrust,  Scliulz  turned  his  attention  to  the  question  of 
economy. 

Steam  turbines  with  several  blade  rings  work  economically 
only  while  they  are  giving  the  largest  possible  output  under  maxi- 
mum boiler  pressure. 

The  cross  section  of  the  steam  passage  is  generally  calculated 
to  suit  the  greatest  output,  and  the  steam  is  led  into  the  first  blade 
ring  at  as  high  pressure  as  possible.  When  the  steam  goes  through 
the  other  rings  its  pressure  gradually  diminishes  till  the  condenser  is 
reached,  when,  provided  the  energy  be  well  utilised,  it  becomes  com- 
paratively small. 

If  a  smaller  output  be  demanded  from  the  turbine  with  its 
steam  passages  formed  as  above,  it  becomes  necessary  to  resort  to 
throttling.  By  this,  however,  the  steam  loses  its  pressure  to  a  con- 
siderable extent  even  before  it  reaches  the  first  ring,  and  economy 
is  thereby  sacrificed.  To  meet  this  objection,  Scliulz  devised  means 


21 

of  varying  the  cross  section  of  the  steam  pipes  in  each  separate  ring 
of  blades.  The  entry  of  the  steam  to  the  revolving  parts  is  thereby 
so  regulated  with  reference  to  the  desired  output,  that  the  full  boiler 
pressure  is  employed,  whatever  may  be  the  rate  of  working.  This  is 
effected  by  the  placing  of  a  ring-slide  valve  before  each  ring  of  guide 
blades  or  before  a  portion  of  the  ring  (German  Patent  No.  132,868; 
Class  14c;  March,  1901). 


By  altering  the  position  of  this  valve  we  can  leave  free  a 
varying  number  of  holes  in  the  fixed  rings  for  the  passage  of  the 
steam  to  the  rotating  parts.  In  Fig.  8  the  individual  fixed  rings  are 
stationary,  but  the  ring  slides,  while  arranged  for  simultaneous  ad- 
justment by  a  common  lever,  can  on  occasion  be  moved  separately. 
The  same  regulation  of  the  steam  may  also  be  obtained  by  the  moving 
of  the  individual  blade  rings  relatively  to  their  ring-slide  valves. 


22 

There  is  no  essential  alteration  in  the  operation  of  the  steam 
when  the  rings  of  guide  blades  are  made  moveable,  either  separately 
or  simultaneously,  instead  of  the  ring  slides. 

Fig.  8  shows  a  section  of  a  turbine  constructed  in  this  manner, 
In  Figs.  9  to  12  the  above-mentioned  adjustments  are  depicted. 

The  action  turbine  of  Fig.  8  has  axial  flow  and  is  provided 
with  five  expansion  stages.  Each  of  these  has  three  subsidiary 


Fig.  9. 


speeds.  The  case  (6)  has  a  greater  diameter  at  the  steam  exit 
than  at  the  entrance,  but  the  working- wheels  all  have  the  same 
mean  diameter. 

The  five  wheels  (3)  are  fastened  to  the  common  shaft  (1), 
which  is  supported  by  the  covers  (4  and  5)  at  the  ends  of  the  turbine. 
Each  wheel  bears  three  revolving  blade  rings  (2),  corresponding 
with  the  speed  stages.  The  first  fixed  blade  ring  of  each  stage  is  ad- 
justable, and  is  placed  on  the  corresponding  partition  wall.  The  two 
others  are  formed  of  blades  (15)  arranged  in  ring  fashion  round  the 


inner  periphery  of  the  case.  On  the  cover  (4)  is  the  chest  for  the 
introduction  of  the  steam ;  on  the  cover  (5)  is  the  chest  for  its  exit. 
The  direction  of  the  steam  flow  is  shown  by  arrows.  The  different 
expansion  stages  are  formed  by  the  partition  walls  (7)  (Fig.  9). 
They  reach  nearly  to  the  shaft,  and  the  clearance  space  being  so 
small,  no  appreciable  loss  of  steam  can  there  take  place.  The  ring 
slide  (8)  and  the  corresponding  adjustments  are  represented  in 
Fi<r.  10. 


Fig.  10. 


Fig.  11  is  an  expansion  drawing,  showing  the  relative  posi- 
tions of  the  holes  in  one  of  the  ring  slides  and  in  the  corresponding 
partition  wall  when  the  output  is  at  a  maximum  and  when  it  is  at  a 
minimum  respectively. 

As  shown  in  Fig.  10,  the  ring  slide  carries  on  the  upper  part 
of  its  circumference  a  number  of  tcoth  (9),  fitting  into  the  toothed 
wheel  (10),  which  can  rotate  about  the  axis  (11).  The  slide  valve  is 
moved  by  the  adjusting-lever  (12),  and  its  position  is  given  by  the 


24 

scale  (13).  The  divisions  through  which  the  axis  (11)  is  moved  are 
denoted  by  14.  The  adjusting  apparatus  on  the  partition  is  shown 
in  Fig  9.  The  adjusting-rod  (16)  and  the  spindle  (11)  pass  through 
ordinary  stuffing  boxes. 


Fig.  11. 


In  this  turbine  the  partitions  have  28  entrance  holes  or  nozzle- 
like  channels  placed  at  equal  intervals  and  having  the  same  cross- 
section.  The  ring  slides  have  also  28  openings  which,  though  alike 
in  each  quadrant,  vary  in  size  and  distance  apart.  In  Fig.  11  two 
such  quadrants  are  shown  developed  on  to  a  plane. 


The  distances  between  the  openings  are  so  chosen  that  in  the 
extreme  position  all  the  seven  st?am  holes  arc  open  and  the  corres- 
ponding expansion  stage  in  question  undergoes  complete  impinge- 
ment. If  the  valve  be  moved  in  the  direction  shown  by  the  arrows, 
the  holes  on  the  left  of  each  quadrant  are  closed.  If  the  valve  be 
moved  further  still,  into  the  position  shown  in  the  lower  half  of  Fig. 


25 

11 ,  the  steam  only  enters  through  one  hole  in  each  quadrant.  Hence 
.a  turn  of  the  lever  12  through  one  division  always  opens  or  closes 
four  holes. 

By  means  of  the  partition  walls  and  ring  slides  of  Figs.  9  and 
10  we  may,  therefore,  obtain  either  a  complete  or  a  partial  flow  of 
steam.  We  can,  however,  partially  cut  the  steam  off  by  another 
method,  as  is  evident  from  Fig.  12.  This  latter  device  has  the  advan- 
tage that  the  steam  from  leading  channels  or  nozzles,  which  are 
.arranged  close  to  one  another,  is  directed  against  the  work  ing- wheel 
in  question  in  a  single  stream. 


Fig.  12. 


If  the  ring  slide  is  to  be  worked  automatically,  the  lever  (12) 
is  connected  with  a  powerful  governor.  The  partitions  are  adjust- 
able separately,  as  before  stated.  We  are,  therefore,  able  to  regulate 
the  width  of  the  steam  passage  in  each  partition  and  hence  for  each 
•expansion  stage  separately.  If,  for  example,  all  the  holes  are  open, 
we  can  by  moving  one  or  other  of  the  partitions,  increase  the  pres- 
sure of  the  steam  leaving  the  corresponding  expansion  stage,  and 
£O  secure  the  best  economy  for  the  desired  output. 


W  Grade. 


2nd  Grade 


10th  Grade 


Measurements  in  Mm. 
(i  Mm.=o'03937  ins.) 

Fig.  18. 


27 

Fig.  13  shows  the  construction  of  the  ring  slides  and  parti- 
tions, and  their  positions  in  the  turbine.  The  openings  in  them  are 
also  shown  in  detail. 

To  prevent  the  steam  from  passing  along  the  shaft  from  one 
expansion  stage  to  the  next,  the  corresponding  borings  in  the  walls- 
are  edged  with  saw-like  teeth.  The  steam  vortices  and  the  friction 
so  caused  reduce  the  loss  of  steam  considerably.  In  addition,  a 
special  packing-ring  is  provided  at  each  partition. 


The  advantages  of  Schulz'  new  designs  have  been  already 
recognised  by  many  German  firms,  who  are  now  building  turbines 
on  his  system. 

A  larger  type  for  outputs  of  from  500  to  800  horse-power  and 
2,000  revolutions  per  minute,  is  given  in  Fig.  14  This  turbine  has- 
four  expansion  stages,  each  writh  two  subsidiary  speed  stages.  In 
regard  to  the  division  into  pressure  and  speed  stages,  every  other 
possible  variation  of  these  may  here  be  made.  Also,  the  steam  flow 
may  be  either  axial  or  radial,  and  may  be  partial  in  some  of  the 
stages  and  complete  in  others.  An  example  of  a  radial  turbine  of 
three  expansion  stages  and  three  subsidiary  speed  stages,  with  special 
regulating  apparatus  and  radial  flow,  is  shown  in  a  diagram  of  the 
above-mentioned  patent  No.  132,868.  The  preference,  however,  in 
this  case  given  to  axial  flow. 

In  the  turbine  of  Fig.  14,  the  driving  steam  is  sent  through 
the  fixed  and  moving  blades  very  effectively.  The  widths  of  the 
holes  and  the  number  of  these  in  the  various  partitions,  as  well  as 
the  number  of  expansion  and  speed  stages,  are  in  all  cases  adjusted 


to  the  requirements  in  regard  to  available  boiler  pressure,  number  of 
revolutions  per  minute,  £c. 

Fig.  8  shows  a  similar  turbine  with  five  expansion  stages, 
<?ach  having  three  speed  stages. 

The  action  turbine  in  Fig.  14  is  designed  for  a  stationary 
plant.  It  will,  however,  serve  just  as  well  for  warships  and  mer- 
chant vessels.  It  will  give  both  large  and  small  outputs  with  high 
or  low  peripheral  velocities,  and  will  work  at  the  highest  pressures. 
It  should  be  especially  noticed  that  the  efficiency  of  these  turbines  is 
not  sensibly  diminished  even  when  the  output  and  peripheral  velocity 
are  small.  It  is  only  necessary  that,  with  due  consideration  to  the 
conditions  in  each  case,  the  expansion  stages  be  fairly  numerous. 
Under  all  circumstances,  however,  Schulz'  action  turbines  will  not 
need  more  than  the  minimum  number  of  blades  and  wheels  usually 
adopted  for  the  purpose  in  hand,  so  that  the  cost  of  construction  is 
not  excessive. 

In  the  turbine  shown  in  section  (Fig.  14)  the  regulation  of  the 
steam  in  the  first  expansion  stage  is  effected  by  a  number  of  small 
stop  valves.  In  the  other  expansion  stages  the  steam  supply  is  con- 
trolled by  ring  slides,  which  are  placed  immediately  in  front  of  the 
groups  of  nozzles  in  the  partitions  (see  Fig.  12).  Thus  the  cross- 
section  of  the  steam  passages  is  suited  to  the  work  required.  The  ring 
slides  may  be  adjusted  by  a  cogged  wheel  system,  by  worm  gearing, 
or  by  levers.  The  governor  is  placed  on  the  free  shaft  wheel  near 
the  stop-valve  and  the  apparatus  for  moving  the  ring  slides ;  these 
latter  are  adjusted  by  a  very  simple  device.  The  governor  can  be 
arranged  so  as  to  adjust  both  the  ring  slides  and  the  stop  valves,  or 
it  may  be  made  to  act  only  on  the  latter. 

The  turbine  can  be  divided  horizontally  into  equal  halves. 
It  is  made  of  cast  iron  or  cast  steel,  or,  in  very  small  engines,  of 
bronze.  The  guide  wheels  or  partitions  are  made  of  the  same 


80 

material,  and  are  placed  steam-tight  in  the  case.  The  working- 
wheels  are  of  steel,  accurately  turned  on  the  lathe  and  well  balanced. 
The  revolving  blades  are  of  delta-metal ,  and  are  strongly  and  simply 
attached  to  the  wheel  ring  by  a  specially  contrived  method.  Com- 
paratively wide  clearance  spaces  are  left  between  the  fixed  and  the 
rotating  parts,  and  even  when  highly  superheated  steam  is  em- 
ployed, no  trouble  due  to  the  rubbing  of  the  blades  against  each  other 
or  to  such  like  causes  can  arise. 


Measurements  in  Mm. 
(i  Mm.  —0-03937  ins.) 


Fig.  15. 

Fig.  15  shows  the  method  of  attaching  the  fixed  and  moving 
blades  in  the  older  turbines  of  the  year  1900.  These  were  dove- 
tailed into  suitable  grooves  and  fixed  firmly  by  a  special  method 


Fig.  16. 


Measurements  in  Mm. 
(i  Mm. =0-03937  ins). 


Fig.   17. 


Such  fixing  is  not  effected  in  the  more  modern  types  by  the  caulking 
tight  of  the  distance  pieces,  since  it  is  difficult  in  this  case  to  avoid  a, 
twisting  of  the  hlades.  Besides,  if  the  positions  of  the  blades  be 
altered  they  cannot  be  recovered. 

Here  also  we  see  the  saw-like  grooves,  which  create  vortices 
in  the  axially  flowing  steam.  These  tend  to  prevent  loss  at  the 
clearance  space  between  the  case  and  the  guide  blades  and  between 
the  latter  and  the  working- wheel.  In  recent  times,  however,  less 
stress  has  been  laid  on  this  point.  The  labyrinth  apparatus  closes 
the  shaft  at  its  exit  from  the  case. 

In  Figs.  16  and  17  are  shown  the  constructions  of  the  older 
labyrinth  stuffing  boxes,  which  closed  the  shaft  of  the  Schulz  tur- 
bine. These  stuffing  boxes  are  extended  for  a  considerable  distance 
along  the  shaft,  so  as  to  make  the  path  of  the  steam  in  the  labyrinth 
as  long  as  may  be.  Fig.  16  shows  one  of  these  stuffing  boxes,  in 
which  the  labyrinth  is  formed  by  two  cylindrical  castings  fitting  into 
each  other  with  rings  screwed  to  them.  The  inner  casting  is 
fastened  to  the  shaft  by  means  of  an  arrangement  of  screws,  placed 
axially.  The  labyrinths  may  be  thus  regulated,  so  that  the  spaces 
left  on  one  side  of  the  rings  are  as  little  as  7lo  inch,  while  those 
left  on  the  other  side  are  comparatively  larger  and  can  serve  as  steam- 
chambers. 

Fig.  17  also  shows  a  packing  of  Schulz'  design.  Here  the 
stuffing  box  is  composed  of  a  number  of  well-fitting  rings.  All  these 
are  placed  on  a  common  cylindrical  casting  and  are  kept  in  place 
by  a  ring  at  the  end.  The  labyrinths  are  here  formed  by  the  peculiar 
cross  section  of  the  individual  rings.  Schulz'  new  labyrinths  differ 
from  these  types  chiefly  in  the  shape  of  the  rings  screwed  to  the 
casting. 

As  in  all  action  turbines,  the  steam  pressure  in  each  expansion 
stage  is  the  same  on  both  sides  of  each  working-wheel.  A  consider- 
able end  thrust,  such  as  we  find  in  multi-stage  reaction  turbines  is 


34 

in  this  case  impossible.     Counteracting  pistons  and  similar  devices 
can,  therefore,  be  dispensed  with. 

We  see,  then,  that  the  new  Schulz  turbines  satisfy  all  require- 
ments; they  are  reliable  in  working,  simple  in  design,  and  very 
economical  in  use  of  steam,  employing  the  full  available  pressure 
for  every  variation  in  the  output. 


Many  crucial  experiments  have  been  made  on  the  two  steam 
turbines  mentioned  on  page  11  (Figs.  1,  18,  and  19),  which  were 
built  in  the  works  of  the  Germania  in  Teg  el.  The  second,  especially, 
has  been  repeatedly  tested,  both  in  the  workshops  and  in  a  boat  of 
19  tons  displacement  on  Lake  Tegel,  near  Berlin.  This  experi- 
mental boat  was  built  principally  to  test  the  manoeuvring  powers  of 
ihe  new  turbines.  In  December,  1901,  soon  after  the  engine  was 
placed  in  the  boat,  it  was  inspected  by  His  Excellency  Admiral  ron 
Tirpitz,  Secretary  of  State  for  the  German  Admiralty,  and  went 
through  all  its  manoeuvres  without  a  hitch. 

This  turbine  is  shown  in  Figs.  18  and  19.  Fig.  18,  which 
shows  the  external  appearance  of  the  turbine,  is  reproduced  from  a 
photograph  taken  in  the  experimental  room  of  the  workshop.  On 
the  high  pressure  case  may  be  seen  the  adjusting  appliances  for  the 
partitions  (Fig.  9).  '  Within  certain  limits,  these  regulate  the  steam 
pressure  in  the  various  expansion  stages.  Mention  may  also  here 
be  made  of  an  indicator  appliance,  which  enables  graphic  repre- 
sentation to  be  made  of  the  pressure  in  the  various  expansion  stages. 
In  Figs.  21  to  24,  several  diagrams  of  this  kind  are  shown. 


36 

The  apparatus  required  for  this  purpose  consists  of  an  indicator 
stop-cock  to  which  a  large  number  of  tubes  (in  this  case  15)  are 
attached  (see  Fig.  20).  In  Fig.  18  three  of  these  cocks  are  visible. 
With  each  expansion  .stage  of  the  turbine  one  of  them  communicates 
by  means  of  a  narrow  pipe,  so  that,  when  its  cone  is  turned  SUm- 


g.  20. 


ciently  and  a  simultaneous  rotation  of  the  indicating  paper  cylinder 
is  made,  the  curves  shown  in  Figs.  21  and  22  are  described.  The 
three  diagrams  of  Fig.  22  show  that,  even  when  the  cross-section 
of  the  steam  passages  is  reduced  to  a  sixth  of  its  original  size,  the  full 
available  pressure  is  employed  in  the  first  expansion  stage.  The 
abrupt  fall  of  pressure  noticeable  especially  in  Fig.  22,  II.  and  III., 
is  due  to  the  temporary  throttling  of  the  steam  passages  in  the  expan- 
sion stages  in  question. 


37 

Indicator  Diagram,  December,  1900. 
Revolutions  per  minute=2050. 


i"=  18-67  Ibs. 
per  sq.  in. 


Fig.  21. 


Indicator  Diagram,  January  22nd,  1901. 


t\t\3\+\s\e\r\8\»\io\it\n\a\»Vf\ 


1  Atmosphere=14-7061bs.  per  sq.  in. 
Fig.  22. 


Grades  i-io 

are  given  J  passage. 

1310  revolutions. 


Grades  1,5,  and  10" 

are  given  J  passage, 

1440  revolutions. 


Grade  i 

is  given  J  passage. 
1440  revolutions. 


39 

Figs.  23  and  24  show  the  advantages  of  placing  an  indicator 
on  a  turbine,  just  as  do  Figs.  21  and  22.  They  were  drawn  from  the 
pressure  curves  of  the  high  and  lowr  pressure  turbines  when  mounted 
in  the  boat  and  being  driven  at  a  diminishing  speed.  In  one  case 
only  six  passages  were  open  to  the  steam ;  in  the  other  30.  The 
diagrams  show  plainly  how  the  pressure  diminishes  in  the  different 
expansion  stages  as  the  speed  decreases,  and  it  is  noticeable  that,  aa 
the  output  becomes  smaller,  one  expansion  stage  after  another  at  the 
exit  end  of  the  low-pressure  turbine  ceases  to  contribute  anything  to 
the  work  done. 

In  Fig.  23  six  steam  passages  are  open.  Of  the  30  expansion 
stages  25  are  still  in  use  when  the  number  of  revolutions  is  890  per 
minute  ;  22  are  employed  when  the  number  is  770  ;  while  only  19  are 
working  when  the  number  is  as  low  as  300. 

Fig.  19  gives  in  section  the  marine  turbine  of  Fig.  18.  The 
high  and  low  pressure  turbines  are  those  given  in  the  patent  No. 
132,868 ;  the  go-astern  engine  is  that  published  in  the  patent  specifi- 
cation No.  135 ,937  (see  Figs.  6  and  8) .  The  details  of  the  design  are 
shown  in  Figs.  8  to  17. 

The  direct  turbines  of  this  engine  are  axial ;  the  go-astern  tur- 
bine is  both  axial  and  radial.  The  high  pressure  engine  is,  for  the 
most  part ,  an  action  turbine ;  in  the  low-pressure  and  go-astern 
engines  the  reaction  principle  is  employed.  The  end  thrust  is  elimi- 
nated by  the  methods  already  described. 

The  turbine  of  Fig.  18  is  here  illustrated  in  a  tenth  of  its  natural 
size.  It  weighs,  with  mountings  and  fittings,  only  a  little  over  a 
ton,  and  since  its  output  is  230  horse-power,  its  weight  per  horse- 
power is  only  about  11  Ibs.  The  case  is  made  of  cast  iron  and  ii 
divided  horizontally.  The  working-wheels  are  of  steel  and  the 
blades  of  the  well-known  delta-metal.  The  boat  used  to  test  this 
engine  was  59  feet  long  by  9ft.  3ins.  broad,  and  had  a  mean  draught 
of  4ft.  Sins.  The  diameters  of  the  various  propellers  (which  were 


JO 


r  f 


Q     .9 


-11 


§   d 

CS  £4 

I- 1  « 

-*->        r    i  '  ^ 

O  M 

b  g'  s 


ll- 

I  i 


H 


42 


Fig.  25. 


49 


Fig.  26. 


44 

used  both  singly  and  in  pairs  during  the  test)  varied  from  12  to  16£ 
inches,  while  the  number  of  revolutions  per  minute  varied  from  1,000 
to  2,200.  The  greatest  speed  was  more  than  13  knots,  the  highest 
average  over  the  measured  mile  on  Lake  Tegel  being  12'35  knots. 
No  vibration  was  felt  even  at  the  highest  obtainable  speed.  The 
boat  manoeuvred  satisfactorily,  and  the  engines  worked  perfectly 
throughout  the  trials. 

The  results  obtained  in  the  test  are  given  in  Table  III. 

The  economy  of  this  comparatively  small  turbine  may  be 
gathered  from  the  curves  of  Figs.  25  and  26.  Especially  at  speeds 
above  11  knots  a  comparatively  low  consumption  of  fuel  is  noticeable. 
The  abscissae  in  Fig.  25  represent  numbers  of  revolutions ;  these 
range  from  1,000  to  2,500  per  minute.  In  Fig.  26  the  abscissae  give 
the  number  of  knots  per  hour. 

Curve  1  gives  the  number  of  revolutions  per  minute. 

Curves  2  and  3  give  the  mean  peripheral  velocities  of  the  first 
and  last  working-wheels  of  the  turbine. 

Curve  4  gives  the  speed  of  the  boat  in  knots. 

Curve  5  gives  the  screw-thrust  when  the  boat  is  moored  and 
the  engine  is  driving  ahead. 

Curve  6  gives  the  same  when  the  engine  is  driving  astern. 

Curve  7  gives  the  corresponding  thrust  when  the  boat  is 
moving. 

Curves  8  and  9  give  the  work  done  by  the  screw  when  the  boat 
is  stationary  and  when  it  is  in  motion  respectively. 

Curves  10  and  12  give  the  steam  consumption  per  hour. 

Curves  11  and  13  give  the  steam  consumption  per  horse-powei 
per  hour. 


45 

The  excess  pressure  of  the  driving  steam  at  this  trial  varied 
approximately  from  200  to  213  Ibs.  per  square  inch.  The  super- 
heating of  the  steam  was  generally  about  160  to  180  cleg.  F. ;  in 
some  cases,  however,  it  amounted  to  more  than  780  deg.  F.  The 
vacuum  was  never  more  than  9'4  Ibs.  per  square  inch.  A  better 
vacuum  could  not  be  obtained,  owing  to  the  insufficient  output  of  the 
air-pump. 

When  the  comparatively  small  peripheral  velocities  of  the 
first  and  last  turbine  wheels  (100  and  165  feet  a  second)  are  con- 
sidered, the  results  shown  by  Table  III.  and  by  the  curves  in  Figs. 
25  and  26  must  be  considered  excellent.  With  an  output  of  195 
horse-power  and  a  speed  of  2,200  revolutions  per  minute,  only  22  Ibs. 
of  steam  per  horse-power  per  hour  were  used,  in  spite  of  the  bad 
vacuum  of  9'4  Ibs.  per  square  inch.  The  brake  trials  in  the  Tegel 
workshop  during  June,  1901,  in  which  a  higher  vacuum  was  at 
disposal,  gave  an  appreciably  larger  output.  In  fact,  for  every  extra. 
Ib.  per  square  inch  in  the  vacuum,  the  turbine  gave  respectively 
13'0,  13'7,  and  15'1  extra  horse-power  when  the  numbers  of  revolu- 
tions per  minute  were  2,000,  2,200,  and  2,600.  Allowing  for  this, 
we  get  an  additional  output  of  240  horse-power  when  the  number  of 
revolutions  is  2,200  per  minute,  while  the  steam  consumed  per  hour 
for  each  horse-power  of  output  is  17'8  Ibs.,  instead  of  22  Ibs.  (see 
Table  IV.) 

The  steam  used  during  these  experiments  in  the  various  auxi- 
liary engines  was  led  into  the  low-pressure  turbine,  so  that  its  energy 
could  be  completely  utilised.  The  steam  consumption  in  these 
auxiliary  engines  is  not  included ;  it  was  found  by  special  investiga- 
tions to  be  about  880  Ibs.  per  hour.  The  economy  of  the  turbine  is 
considerably  increased  if  this  steam  is  also  reckoned,  as  in  the  curves- 
of  Figs.  25  and  26,  where  the  steam  consumption  for  the  subsidiary 
engines  is  denoted  by  the  shaded  portion. 

According  to  the  latest  trials  of  the  "Turbinia,"  fitted  with 
large  Parsons  turbines,  the  steam  consumption  with  the  highest  out- 
put of  1 ,600  to  1 ,700  horse-power  is  about  20  Ibs.  per  horse-power  per 


46 

hour.  It  must  be  noticed,  however,  that  these  turbines  are  appre 
ciably  larger  than  the  Schulz  turbines  under  discussion.  Moreover, 
according  to  page  193  of  "Engineering,1'  August  1st,  1903,  the 
velocities  of  the  steam  in  the  first  and  last  blade  rings  of  the  Parsons 
turbine  were  150  and  280  feet  per  second  respectively,  the  number 
of  revolutions  being  2,200  and  3,000  a  minute.  The  velocity  in  the 
Schulz  turbine,  on  the  other  hand,  was  only  100  to  165  feet  per 
second,  when  the  output  and  speed  of  revolution  were  at  their 
maxima. 

The  results  of  Table  I.  apply  to  the  turbine  of  Fig.  1 :  those  of 
Tables  II.,  Ill,  and  IV.  to  the  turbine  of  Figs.  18  and  19. 


TABLE    I. 
EXPERIMENTAL  TURBINE  No.  1  DRIVING  A  DYNAMO.     1899. 


Number  of  Experiment. 
Boiler  pressure  ..         ..         ..         ..         ..         .. 

12345 
Excess  pressures  in  atmospheres, 

15         15       11         7-4       5-2 

Steam  pressure  in  entrance  chamber            ..         .. 
Pressure  behind  first  expansion  stage 
Pressure  in  passage  from  1st  to  2nd  turbine 
Pressure  in  middle  expansion  stage  of  2nd  turbine.  . 
Number  of  revolutions  per  minute     .. 
(Voltage          
10  1  Current  in  Amperes            
(Kilowatts          
Output  lElectric  Horsepower             

12        12       10-5     7           5 
9          8-9      7-8     4-8       3-5 
2          2         1-9     1-15     0-7 
0-25     0-25    0-2     0          0 
1700     1400     1200      980      800 
150      160     100      80        75 
250      170     200     110        70 
37-5     27-2   20        S'S       5-25 
51        37      27-2   11-97     7-14 

The  steam  turbine  weighs,  with  all  the  mountings  and  fittings,  about  12£  cwts. 


2 

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No.  of  Experiment. 
No.  of  Revolutions  per  Minute. 

Pressure  behind  main  turbine 
,,  in  condenser  .  . 
Horse-power  .  . 

Pressure  behind  main  turbine 
„  in  condenser  .. 
Horse-power  .  . 

Pressure  behind  main  turbine 
,,  in  condenser 
Horse-power  .  .  .  . 

Pressure  behind  main  turbine 
,,  in  condenser  .  . 
Horse-power 

Pressure  behind  main  turbine 
,,  in  condenser 
Horse-power  .. 

Pressure  behind  main  turbine 
..  in  condenser 
Horse-power  .  . 

'$ 

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2 

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TABLE    III. 

EXPEPIJIENT    IN    THE    BOAT    WITH    TuBHINK    No.    2. 


1 

2 

3 

4 

5 

C 

7 

8 

9 

10 

11 

1-2 

13 

ii 

Mean  peri- 
pheral velocity 
in  feet  per 
second 

Boat's 
speed 
in 
kncts. 

Screw  thrust  in  cwts. 

Output  of 
screw  in 
horse-power 

Hourly  consumption  of  steam 
in  Ibs. 

of      I       of 
first    !    last 

when  stationary 

when 

when 
station- 

when 
mov- 

when stationary]    when  moving 

per    1 

per 



for- 

back- 

moving 

ary. 

ing. 

Total 

horse-  j  Total. 

horse- 

turbine wheel. 

wards. 

wards. 

power.  ] 

power. 

1000 

46-2 

73-8 

7-4 

7'G 

7-6  |      6-8 

33-7 

28-5 

2380 

70     !  1950 

68 

1400 

G47 

103-3 

9-1 

13-0      12-1 

10-9 

82-1 

69 

3700 

45 

2730 

40 

1800 

83-1 

132-8 

10-7 

18-5 

16-9 

15-4 

1504 

126-5 

5070 

34 

3500 

27 

2200 

101-6 

102-4 

12-35 

20-1 

195 

4300 

22 

2300 

12-6 

21-2 

211 

4500 

21 

2400 

110-9 

177-2 

13 

22-4 

228 

4G70       20-5 

Vacuum  =  5  of  an  atmosphere. 


TABLE     IV. 


l 

9 

12 

13 

per  square  in. 

No.  of  Revolutions 

Effective  Horse- 

Steam 

Consumption  in  Ibs 

per  minute. 

power. 

per  hour. 

per  horse-power. 

9-4 

195 

22 

2,200 

4,300 

12-8 

240 

17-8 

49 

After  the  experiments  with  the  above-mentioned  boat  had 
been  carried  through  successfully,  Schulz  turned  his  attention  to 
the  construction  of  an  engine  suitable  for  all  men-of-war,  including 
battleships,  cruisers,  and  torpedo  boats. 

Merchant  ships,  whether  they  be  cargo,  passenger,  or  mail 
boats,  steam  steadily  at  their  highest  possible  speed,  except,  foi 
instance,  when  the  weather  is  rough  or  foggy.  The  construction  of 
turbines  for  such  vessels,  therefore,  offers  no  special  difficulties.  With 
men-of-war  the  case  is  very  different ;  their  engines  must  always  be 
prepared  to  develop  their  utmost  power,  but  this  output  is  required 
but  seldom,  and  then  only  for  short  spaces  of  time.  Moreover,  in 
warships  it  is  demanded  that  the  consumption  of  fuel  in  proportion 
to  horse-power  be  the  most  economical  when  the  output  is  small  or 
moderate,  say  from  TV  to  ?  of  its  maximum  value. 

The  multi-stage  marine  turbines  constructed  by  Parsons  and 
Rateau  use  appreciably  more  coal  in  proportion  to  the  output  when 
the  latter  is  small,  than  when  it  is  large.  On  the  well-known  sea- 
going torpedo-boats,  "Viper"  and  "Cobra,"  the  consumption  of  fuel 
for  small  outputs  was  nearly  twice  as  great  as  in  the  sister-ships, 
"Albatross"  £c.,  which  were  fitted  with  reciprocating  engines. 

Rateau  and  Parsons  before  him  have  combined  reciprocating 
•engines  with  large-sized  turbines  for  use  when  only  a  small  output  is 
required.  Parsons,  however,  has  gone  back  to  pure  turbine  engines. 
The  steam  consumption  on  the  German  sea-going  torpedo-boat, 
"S  125,"  fitted  with  Parsons'  turbines,  cannot  even  yet  be  accurately 
determined,  the  air-pump  having  at  the  first  series  of  trials,  proved 
unsatisfactory.  Several  months  were  then  wasted  while  the  latter 
was  being  replaced,  and  since  other  mishaps  have  meanwhile  inter- 
vened to  delay  the  trial  trips,  it  may  be  still  some  time  before  the 
coal  consumption  is  determined.  However,  it  is  fairly  evident  from 
the  reports  on  the  first  trials,  that  the  above-mentioned  conditions 
will  not  be  satisfactorily  fulfilled  by  this  engine. 

D 


50 

Schulz  has  now  patented  another  marine  turbine  (No. 
160,863;  Class  65a ;  April  23rd,  1901),  which  is  shown  in  Figs.  27 
and  28.  This  plant  is  arranged  for  a  single  shaft  only.  In  ships- 
with  several  screws  it  is  proposed  to  use  one  of  these  engines  for  each 
shaft. 

In  front  of  the  main  turbine  a  number  of  turbine  wheels  are 
placed,  which  can  also  be  separated  into  groups.  The  steam  is  cut 
off  from  these  when  the  output  is  large,  so  as  to  prevent  them  from. 


Go-asten 
Turbine. 


Disconnectable 
Auxiliary  Turbines. 


Fig.  '27. 


sharing  in  the  work.  The  smaller  the  output,  the  larger  is  the 
number  of  auxiliary  turbines  which  contribute  their  share  to  the 
work  done.  When  the  output  is  at  its  smallest,  the  steam  passes 
through  the  stop-valve  1  into  the  turbine  d,  the  remaining  stop- valves 
3,5,  7,  being  then  closed,  and  the  exit  valves  2,4,6  opened.  When 
the  output  is  larger,  the  smallest  turbine  d  is  cut  off  by  the  closing  of 
the  stop-valves  1  and  2,  and  the  steam  passes  by  the  valve  3  into  the 


51 

second  turbine  c.  On  further  increase  of  the  work  the  turbine  c  is 
also  cut  off  by  the  closing  of  the  valves  3  and  4  ;  and  when  the  output 
is  at  its  maximum,  all  the  valves  1  to  7  are  closed,  so  that  the  steam 
only  enters  the  main  turbine  a. 

By  this  arrangement  an  increasing  number  of  turbines  contri- 
bute their  share  of  work  as  the  output  diminishes,  so  that,  owing  to 
the  increasing  number  of  expansions,  the  difference  of  steam  pres- 
sure in  two  successive  expansion  stages  is  always  very  small.  The 
initial  pressure  may,  therefore,  be  so  high  that  the  difference  between 
the  pressures  at  the  entrance  and  exit  passages  respectively  of  the 
engine  always  maintains  its  maximum  value. 


Fig.  28. 


If,  then,  the  auxiliary  turbines  be  of  suitable  size,  the  full 
energy  of  the  steam  is  utilized,  whatever  may  be  the  speed,  and  due 
economy  is  observed. 

It  is  indifferent  whether  the  whole  apparatus  is  enclosed  in  a 
single  case  or  whether  each  separate  turbine  has  its  own  cover. 

Fig.  28  shows  a  section  of  this  compound  engine.  The 
rotating  wheels  1  to  4  are  placed  on  the  common  shaft  15,  and  work 
directly  ;  the  wheel  5  is  for  motion  astern.  To  regulate  the  end 


52 

thrust  the  steam  flows  in  opposite  directions  through  the  largest 
turbines  (4)  and  the  smaller  ones  (1,  2,  3).  The  main  stop-valve  7 
allows  the  steam  for  forwards  motion  to  flow  through  the  pipe  10 
and  the  valve  11,  through  the  pipes  10  and  19  and  the 
valve  30,  or  through  the  pipes  10,  19,  and  25,  and  the 
valve  26,  into  the  various  turbines.  The  steam  for  reversing  passes 
through  the  pipes  8  and  9.  The  pipe  29  allows  steam  to  pass  from 
turbine  1  to  turbine  2.  The  circular  passages,  18,  23,  24,  27,  and  12, 
serve  as  chests  for  the  steam  before  its  entrance  into  the  various  tur- 
bines ;  the  passages,  28,  31,  21,  and  13,  serve  as  exit  chests.  The 
steam  is  led  to  the  condenser  through  the  pipe  13. 


The  Parsons  turbine  is  at  present  the  most  popular  for  marine 
purposes.  It  is,  therefore,  of  interest  to  compare  this  engine  with 
the  Schulz  turbine,  especially  as  lawsuits  have  been  brought  by  the 
former  engineer  against  the  latter  for  infringement  of  patent.  These 
lawsuits  were  decided  in  favour  of  the  defendant. 

The  plaintiff  relied  chiefly  on  the  English  patent,  11,223/97, 
with  which  the  German  patent  No.  103,559  corresponds.  He 
maintained  that  Schulz'  arrangement  had  been  already  protected  by 
this  patent  and  that  consequently  Schulz'  patent  No.  160,863  (Figs. 
27  and  28)  was  invalid. 

Parsons'  arrangement  in  the  patent  No.  103,559  is  shown  in 
Pigs.  29,  30,  and  31.  Though  he  has  made  many  laborious  and  costly 
•experiments  to  get  a  low  steam  consumption  in  both  low  and  high 
outputs,  he  has  failed,  and  Schulz  was  the  first  to  obtain  a  satis- 
factory solution  of  the  problem.  Parsons  subsequently  followed  in 
the  path  already  trodden  by  Schulz. 


53 

In  Parsons'  attack  en  Schulz'  system  (Figs.  27  and  28)  atten- 
tion was  first  called  to  an  article  by  the  naval  engineer,  Herr 
Grauert,  in  the  Marine- Rundschau,  of  January,  1904.  Notice  was 
also  taken  of  Grauert's  remarks  in  "Steam  Turbines,"  by  Dr.  A. 
Stodola,  relating  to  the  economy  of  steam  necessary  for  warships. 


Fig.  29. 


Now  in  this  article  we  read  : — 

"For  constant  output,  the  fuel  burnt  per  horse-power  is  appre- 
ciably higher  at  low  rates  of  revolution.  If,  however,  the  output 
and  speed  of  rotation  fall  simultaneously,  the  consumption  of  steam 
is  altered  but  little." 


Fig.  10. 


55 

The  first  of  these  two  statements  would  be  intelligible  only  if 
it  were,  under  normal  circumstances,  possible  for  the  output  of  a 
marine  engine  to  remain  constant  when  the  speed  altered.  More- 
over, it  is  easily  proved  that,  when  output  and  speed  diminish,  the 
fuel  consumption,  so  far  from  being  lessened,  is  very  considerably 
increased. 

Grauert's  diagram  is  reproduced  in  Fig.  32. 

Now  we  must  not  suppose  that  in  the  production  of  this  diagram 
three  equal  turbines  of  1,500  horse-power  were  used,  working  on  a 
single  shaft  parallel  to  the  boiler.  For  to  use  a  second  and  a  third 
engine  of  1,500  horse-power  directly  the  required  output  exceeded 
1,500  and  3,000  horse-power  respectively  would  be  too  extravagant  a 
method  to  be  of  any  practical  use. 


.  31. 


The  experimental  trials  on  which  Grauert's  diagram  was 
based  were,  no  doubt,  made  on  a  normal  stationary  Parsons  turbine, 
in  which  it  was  possible  to  alter  the  rate  of  revolution  without  change 
of  output.  A  very  similar  diagram  is  found  on  page  37  of  a  paper 
circulated  by  Parsons'  representatives,  "The  steam  turbines  of 
Brown,  Boveri,  and  Parsons  for  stationary  and  marine  engines." 


CONSUMfTtON  Of  STEAM  n*  H  P'ei  HOVK  >»  *• 

(f  ffe    *  2-2  Let) 
Fig.  32. 


S7 

The  curve  given  here  for  light  load  is  that  used  in  Grauerfs  diagram. 
It  is  only  applicable  to  marine  engines  with  uncoupled  shafts,  and  is- 
worthless  for  trials  of  steam  consumption  on  marine  engines,  so  that 
on  this  ground  also  we  assume  that  a  stationary  Parsons  turbine  is- 
ref erred  to.  If  this  assumption  be  correct,  the  conclusions  drawn 
from  the  diagram  are  of  value  only  when  applied  to  the  driving  of 
stationary  engines,  and  not  in  the  case  of  marine  engines  working  at 
markedly  varying  speeds. 

In  ships'  turbines  it  is  impossible  to  maintain  constant  output 
with  varying  speed  of  revolution.  In  such  engines  the  output  varies 
as  the  cube  of  the  speed  of  rotation  ;  for  example,  if  the  speed  be 
halved,  the  output  will  have  only  an  eighth  of  its  former  value. 

Now  the  diagram  shows  four  outputs  of  a  single  turbine  for 
speeds  of  revolution  differing  but  little  from  each  other.  To  arrive- 
at  a  satisfactory  conclusion  we  must  consider  the  lower  speeds  also. 
The  diagram,  however,  has  a  very  different  aspect  when  it  is  ex- 
tended so  as  to  cover  the  smallest  ordinary  speeds  as  well  as  the 
higher  ones. 

It  is  usual  to  take  40  %  of  the  maximum  for  the  lowest  speed 
ordinarily  employed.  Since  we  may  suppose  the  speed  roughly 
proportional  to  the  number  of  revolutions  in  a  given  time,  the  limits- 
to  be  considered  lie  between  600  and  240  rotations  per  minute. 

Now,  in  a  marine  engine  the  output  (as  mentioned  before) 
varies  approximately  as  the  cube  of  the  number  of  revolutions  per 
minute,  and  the  600  revolutions  per  minute  necessary  for  the  maxi- 
mum output  of  4,500  horse-power  with  a  steam  consumption  of 
73,000  Ibs.  an  hour  (about  IG'l  Ibs.  per  horse-power  per  hour),  being 
taken  as  a  basis,  the  consumptions  for  other  outputs  work  out  as- 
given  in  Table  V.,  here  following.  We  assume  that  in  the  diagram 
an  ordinate  of  1  mm.  represents  an  hourly  use  of  1,100  Ibs.,  or  a, 
consumption  per  horse-power  per  hour  of  I'l  Ibs. 


58 
TABLE  V. 


Output  in  horse-power. 

No.  of  revolutions  per 
minute 

600 

Steam  con 
Per  hour. 

sumption. 

Per  horse-power 
per  hour. 

4,500 

73,0:0 

16-1 

3,000 

522 

51,800 

17-3 

1,590 

5G2 

415 
300 

3G,400 
28,800 

24-2 
4-2-3 

288 

240 

18,700 

64-S 

Grauert's  diagram  reproduced  in  Fig.  32  was  extended  with 
the  help  of  this  table.  The  curves  thereby  added  show  clearly  the 
great  difference  of  output  and  corresponding  fuel  consumption  in 
one  and  the  same  turbine  for  greater  and  smaller  speeds. 

The  trials  on  the  well-known  "Turbinia,"  constructed  at  the 
Parsons  works,  have  given  similar  results.  Prof.  E wing  has  col- 
lected these  at  the  instance  of  the  Marine  Steam  Turbine  Company. 
They  were  published  in  a  paper  read  by  Parsons  before  the  Institu- 
tion of  Naral  Architects  on  June  26th,  1903,  and  are  given,  amongst 
other  matters,  on  page  185  of  the  "Marine  Engineer"  for  1903. 
Table  VI.  contains  these  results. 


TABLE    VI. 


Output  in  horse-power 
referred  to  the  resistance 
of  the  ship. 

*»r>,Wi  in        '      S'eam  consumption  per 
knits                  horse-power  per  hour 
in  )bs.            in  kg. 

Steam  pressure  per 
square  inch 
in  Ibs.         in  aim. 

98n 

on 

23-7              13-0 

1G2              ll'O 

704 

28 

33-0             15-0 

129               8-75 

325 

20 

41-9              19-0 

72               4-9 

184 

in 

52-5              23-8 

47               3-2 

90 

13 

68-3              31-0 

29               2-0 

31                                 10                    88-2              40-0 

13               0-9 

.    (  7  ATAt.=  /+ .  ?JLBS.  f£*  S«  tN.  ) 

Fig.  33. 


60 

In  the  last  column  of  this  table  is  given  the  initial  pressure 
of  the  steam  at  its  entrance  into  the  turbine.  We  see  that  when  the 
output  is  at  its  minimum  the  steam  must  be  throttled  below  atmos- 
pheric pressure  before  it  finds  its  way  into  the  engine.  This  explains 
the  great  losses  of  steam  sustained  by  these  turbines  as  their  output 
diminishes.  Fig.  33  gives  the  results  of  Table  VI.  in  graphical  form. 
Comparison  of  Figs.  32  and  33  showrs  the  similarity  of  the  two- 
Parsons  turbines,  and  proves  that  when  they  are  used  for  ships  the 
steam  consumption  increases  considerably  as  the  work  done  per 
horse-power  per  hour  diminishes. 

It  is  now  quite  evident  without  further  explanation,  why  the 
torpedo-boat  destroyers  "Viper"  and  "Cobra"  consume  nearly  twice 
as  much  fuel  on  an  ordinary  voyage  as  their  sister-ships  "Albatross," 
&c.,  which  are  fitted  with  reciprocating  engines.  The  turbines  of 
the  "Viper"  and  "Cobra"  are  shown  in  Fig.  30  (Fig.  2  of  the  patent 
Xo.  103,559).  Since  it  was  mainly  on  this  patent  that  Parsons  relied 
in  his  lawsuit  against  Schuh,  it  is  sufficiently  shown  that  it  is  not  by 
this  method  that  we  can  solve  the  problem  of  securing  the  same 
economy  with  small  outputs  as  with  large  ones. 

Parsons  also  has  recognised  the  fact  that  the  arrangement  of 
his  patent  Xo.  103,559  cannot  bring  much  success.  This  is  evident 
from  the  circumstance  that  he  had  recourse  to  reciprocating  engines 
for  slow  speeds.  This  system  was  protected  in  the  English  patent 
16,551/1900,  but  also  proved  a  failure.  The  German  Naval  Adminis- 
tration, for  example,  was  averse  to  a  composite  system,  and  Parson t 
then  had  recourse  to  detachable  turbines  en  the  Schidz  pattern. 

S chitl z  had  patented  his  system  in  England  on  April  23rd , 
1901.  Soon  after  the  publication  of  the  patent  specification 
(8,378/1901),  Parsons,  on  August  7th,  1902,  brought  out  the  Eng- 
lish patent  17,391/1902,  which  relied  on  the  principle  of  small  detach- 
able turbines  for  ordinary  voyages,  similar  to  those  in  Scliulz'  pre- 
vious patent,  8387/190].  Parsons'  only  alteration  was  the  intro- 
duction of  additional  steam  into  the  individual  turbines,  by  which  he 


61 

obtained  a  better  graduation  of  the  output  while  sacrificing  the 
advantage  of  greater  economy. 

It  is  true  that  Parsons  described  in  his  patent,  and  fitted  in  the 
•German  torpedo-boat "  S  125,"  and  in  the  English  cruiser"  Amethyst," 
a  system  in  which  the  smallest  turbine  is  cut  off  during  fast  voyages 


Turbines 

for 
Full  Power 


Disconnectable 

Auxiliary  Turbines 

for  Low  Powers. 


Fig   34. 


and  the  steam  led  directly  into  the  second  turbine  (Fig.  37).  In 
this  he  followed  the  Schulz  system.  He  failed,  however,  to  notice  that, 
owing  to  the  distribution  of  auxiliary  turbines  adopted,  the  outer 
shafts  communicated  very  unequal  amounts  of  energy  to  their  screws, 
and  that,  consequently,  the  system  is  quite  unsuited  for  marine 
purposes. 


62 

These  considerations  quite  dispose  of  Parsons1  statement,, 
that  he  had  by  the  method  of  his  former  patent  No.  103,559,  practi- 
cally solved  the  difficulties  arising  from  the  varying  rates  of  speed  at 
which  marine  turbines  must  work.  This  will  be  still  clearer  if  we- 
submit  the  specification  of  the  patent  to  a  searching  examination. 


Fig.  35. 


We  can  only  obtain  the  maximum  economy  with  a  turbine r 
or  with  a  combination  of  turbines,  when  the  expansion  of  the  steam 
from  the  boiler  to  the  condenser  has  a  considerable  range,  and  when 
the  current  in  the  turbine  flows  without  discontinuous  changes  of 
pressure.  For  this  purpose  we  must  give  a  suitable  succession  of 
cross-sections  to  the  passages  by  which  the  steam  is  led  from  its 
entrance  into  the  first  turbine  to  its  exit  into  the  condenser.  To- 


68 

emphasize  the  difference  between  Schulz'  and  Parsons1  turbines,  we 
reproduce  a  number  of  diagrams  in  which,  for  the  sake  of  clearness , 
all  the  turbines  of  the  plant  are  placed  side  by  side.  The  diagrams- 
are  only  intended  to  show  the  variation  of  pressure  as  the  steam 
passes  through  the  turbines,  and  make  no  claim  to  accuracy  in  detail. 


Fiji.  36. 


From  Fig.  34  it  is  quite  clear  that  Schulz'  system  satisfies  the  above- 
mentioned  conditions.  As  we  pass  from  the  maximum  output  to  a, 
lesser  one  and  so  down  to  the  minimum,  we  are  continually  adding 
smaller  and  smaller  turbines.  In  all  cases  the  steam  passes  at  its- 
boiler  pressure  into  the  foremost  of  the  additional  turbines,  and 
undergoes  a  continuous  and  complete  expansion  as  it  passes  through 
passages  of  continuously  increasing  cross-section. 


64 

Now  we  cannot  construct  a  turbine  plant  in  such  a  manner  that 
.•at  every  speed  all  the  working- wheels  contribute  to  the  expansion 
•of  the  steam.  It  is  usual  to  secure  the  most  favourable  case  when 
the  output  is  at  its  maximum,  as  is  apparent  from  the  diagrams.  As 
the  output  is  lessened,  an  increasing  number  of  turbines  at  the  con- 
•denser  end  cease  to  share  in  the  work.  This  is,  however,  inevitable, 
and  does  not  affect  the  general  principle,  that  increase  in  the  number 
•of  turbines  should  accompany  decrease  of  output. 

Parsons  has  attempted  to  secure  an  economical  use  of  fuel  ;it 
till  speeds  by  a  redistribution  of  the  turbines,  but  has  only  actually 
attained  this  in  those  cases  which  in  Figs.  35  and  36  are  num- 
bered I,  VI,  and  VIII.  All  the  remaining  arrangements  fail  to 
secure  a  continuous  expansion  of  the  steam.  It  is  apparent  from  the 
patent  specification  that  Parsons  also,  for  small  outputs,  sends  the 
steam  through  all  the  turbines  one  after  another,  but  it  appears  that 
for  larqe  outputs  he  also  sends  it  through  all  the  turbines  by  a  route 
that  is  several  times  as  long.  If  we  consider  first  of  all  the  method  of 
Fig.  35,  we  see  that,  on  plotting  the  fall  of  pressure,  we  get  a  normal 
curve  only  when  all  the  eight  turbines  are  placed  in  series.  In  II. 
the  turbines  B  and  D  hardly  contribute  any  share  to  the  output, 
while  between  A'  and  B'  and  also  between  C;  and  D'  we  have  an 
•exceptionally  large  fall  of  pressure  without  any  corresponding  per- 
formance of  work.  Fig.  36  shows  the  decrease  of  pressure  due  to  the 
arrangement  of  Fig.  30  (Fig.  2  of  Parsons'  patent).  This  is  the 
system  fitted  on  the  "Viper"  and  "Cobra."  If  we  assume  that  the 
turbines  work  satisfactorily  when  connected  in  parallel  (Fig.  36, 
VI.),  this  can  no  longer  be  the  case  when  all  four  of  them  are  con- 
nected in  series  to  suit  small  outputs.  The  turbines  A  and  D  then 
-do  hardly  any  work — a  fact  which  explains  the  large  coal  consump- 
tion of  these  vessels.  Consideration  must,  moreover,  be  given  to  the 
above-mentioned  inequality  in  the  distribution  of  the  work. 

Similarly,  Figs.  36,  VIII,  IX,  and  X,  prove  that  the  system 
of  Fig.  31  (Fig.  3  of  the  patent  specification)  is  economical  only  when 
Jthe  turbines  are  connected  in  series. 


65 

Except,  then,  in  the  case  of  the  distributions  I,  VI,  and 
VIII  we  cannot  obtain  a  gradual  fall  of  pressure  by  any  of  the 
methods  of  the  patent  No.  103,559.  The  steam  passages  leading 
from  the  boiler  to  the  condenser  will  not  have  properly  graduated 
cross-sections,  and  the  division  of  work  among  the  screw  shafts  will 
be  so  uneven,  that  the  distribution  methods  described  in  the  patent 
specification  cannot  possibly  produce  a  plant  that  will  be  economical 
at  all  speeds. 


For  the  principal  turbines  of  a  plant  on  the  Schulz  system 
(Fig  34)  intended  to  drive  a  large-sized  man-of-war,  from  60  to  90 
working- wheel  blade-rings  are  necessary.  The  number  of  rings  in 
the  auxiliary  turbines  depends  on  the  smallest  output  required.  In 
most  cases  a  distinctly  larger  number  of  rings  is  necessary  for  the 
auxiliary  than  for  the  main  turbines.  If  we  have  found  the  number 
of  blade-rings  required  in  the  principal  turbines,  and  also  the  number 
in  the  other  turbines  suitable  for  the  smallest  reasonable  speed  of 
working,  we  can  evidently  get  every  possible  speed  that  lies  between 
the  maximum  and  minimum  limits.  We  have  only  to  determine 
how  best  to  group  the  blade-rings  of  the  auxiliary  turbines  so  that 
the  various  speeds  may  be  obtained  with  the  greatest  economy. 

In  Fig.  34  is  shown  an  arrangement  of  this  kind  with  three 
detachable  turbines.  For  the  smallest  output  all  three  groups  of 
blades  are  employed.  The  steam  passes  through  each  in  turn,  then 
through  the  main  turbine,  and  so  on,  into  the  condenser.  It  may 
happen  that  the  steam  has  expanded  completely  before  it  has  passed 
the  last  blade-ring.  This  last  ring  will  then  turn  in  the  vacuum 
without  performing  work,  but  the  slight  disadvantage  connected 
therewith  is  inevitable 


66 

If  a  greater  output  be  required,  the  first  auxiliary  turbine  is 
cut  off,  and  the  steam  enters  the  second  one.  For  still  higher  out- 
puts only  one  auxiliary  turbine  is  used,  and  for  the  maximum  only 
the  main  turbine. 

By  this  means  we  can  get  the  best  result  at  every  intermediate 
speed,  provided  we  know  how  to  determine  the  total  number  of  rings 
necessary  for  the  smallest  output  required,  and  how  to  divide  them 
properly  into  the  various  groups. 

If,  now,  an  output  having  the  highest  possible  economy  be 
desired  for  only  one  or  two  given  speeds  besides  the  maximum,  it  is 
natural  to  apply  the  Schulz  system  only  so  as  to  satisfy  these  require- 


Fig.  37. 


ments  and  to  pay  no  attention  to  the  intermediate  outputs.  This, 
however,  in  no  way  detracts  from  the  merits  of  the  new  method  of 
working,  the  inventor  of  which  is  Schulz. 

It  is,  moreover,  a  matter  of  complete  indifference,  whether  his 
auxiliary  turbines  are  mounted  on  the  same  shaft  as  the  main  tur- 
bine, or  whether  they  are  distributed  over  several  different  shafts  and 
connected  by  pipes  of  greater  length.  Schulz  has  given  due  con- 
sideration to  such  arrangements,  and  has  applied  for  further  patents. 


67 

After  the  publication  of  Schulz'  new  system,  Parsons,  as 
mentioned  above,  employed  similar  arrangements.  For  instance, 
in  a  French  torpedo-boat  he  placed  a  turbine  for  ordinary  voyages  in 
front  of  the  main  turbine,  and  in  the  English  cruiser  "Amethyst" 
and  the  German  torpedo-boat  "S  125"  he  built  a  similar  auxiliary 
turbine  in  front  of  the  main  turbine  of  each  of  the  outer  shafts. 

Fig.  37  shows  this  arrangement.  The  two  auxiliary  turbines 
are  denoted  by  1  and  2 :  the  three  main  turbines  by  3,4,4.  When 
the  output  is  at  a  minimum,  the  steam  goes  from  1,  through  2,  to  3. 
Then  it  is  divided  and  passes  through  4  and  4.  If  a  larger  output  be 
required,  Parsons,  following  Schulz'  method,  cuts  out  1,  and  sends 
the  steam  directly  into  2,  and  thence,  by  way  of  3,  to  4  and  4. 


Fig.  38. 


For  turbine  plants  with  four  screw  shafts,  Parsons  solves  the 
problem  in  a  similar  manner.  Fig. 38  shows  the  system  adopted  on 
the  small  German  cruiser  "Lubeck."  The  usual  voyage  speeds  of 
this  vessel  are  11  and  19J  knots  per  hour,  corresponding  with  out- 
puts of  1,400  and  7,000  horse-power  respectively. 

When  the  smaller  speed  is  required,  the  steam  passes  first 
into  the  auxiliary  turbines  1  and  2,  placed  on  the  two  inner  shafts  in 
front  of  the  corresponding  main  turbines.  On  leaving  2  it  is  divided 
and  passes  through  the  main  turbines  3  and  4  on  one  side  of  the  ship 
and  3'  and  4'  on  the  other  side.  For  high  speeds  and  for  some  of 


68 

the  intermediate  ones    1  and   2  are  cut  off,  and  the  steam   passes 
directly  into  3  and  3'. 

In  all  these  cases,  Schulz'  new  principle  of  detachable  turbines 
is  adopted,  but  only  to  a  limited  and,  therefore,  imperfect  extent. 

Moreover,  both  the  plants  of  Figs.  37  and  38  give  rise  to  un- 
even and  asymmetrical  distributions  of  the  work  amongst  the  shafts. 
Besides,  in  the  system  of  Fig.  38  the  central  partition-wall  of  the 
ship  is  pierced  three  times  by  steam  pipes,  including  one  pipe  for  the 
go-astern  engine.  This  interdependence  of  their  two  sides  is  cer- 
tainly unfavourable  for  the  working  of  the  engines. 


We  have  shown  that  m  Schulz'  Marine  Turbine  (Patent  No. 
168,863),  there  is  a  continuous  fall  of  pressure  and,  therefore,  a  per- 
fect use  of  the  available  energy  under  all  possible  circumstances.  In 
Parsons'  system,  on  the  other  hand,  this  is  only  true  for  certain 
special  cases.  Schulz'  method  certainly  gives  the  surest  solution  of 
the  problems  connected  with  the  turbine  engines  of  war  and  mer- 
chant vessels. 

When  the  output  of  a  reciprocating  engine  alters,  the  economy 
does  the  same,  for  it  diminishes  with  diminishing  output.  The 
same  is  true  in  steam  turbine  engines  also. 

Machines  for  stationary  plant  almost  invariably  work  at  speeds 
bearing  constant  ratios  to  the  different  outputs.  These  ratios  vary 
within  narrow  limits,  being  mostly  either  1 :  2  or  1 :  4.  On  this 
speed  of  working  the  economy  of  stationary  engines  chiefly  depends. 
The  case  is  different  with  marine  engines,  and  especially  with  those 
of  men-of-war.  Here  the  speed  may  vary  from  the  maximum  down 
to  the  1/1 5th  part  of  it, 


69 

In  steam  turbines  the  cross-section  of  the  steam  passages  is 
made  just  large  enough  for  the  highest  output,  i.e. ,  for  the  maximum 
consumption  of  steam.  When  the  work  to  be  done  is  smaller,  these 
passages  are  much  too  large.  Since  a  resort  to  throttling  is  here 
necessary,  the  steam  pressure  in  the  first  expansion  stage  must  fall 
abruptly,  and  waste  of  energy  is  always  the  result.  Now  Schuh 
has.  above  all  things,  secured  the  maximum  of  efficiency  at  different 
speeds  by  dividing  the  whole  turbine  complex  into  detachable  por- 
tions and  by  passing  the  steam  into  these  various  turbines  in  such  a 
manner  that  a  state  of  expansion  is  always  present.  When  the  out- 
put decreases,  an  increased  number  of  turbines  or  turbine  drums  come 
into  play.  For  the  minimum  of  work  all  the  turbines  share  in  the 
propulsion. 

The  paradoxical  nature  of  the  arrangement  makes  it  the  less 
surprising  that  this  device  should  have  escaped  the  notice  of  the 
earlier  designers  of  marine  turbines,  Parsons  and  Rateau.  Schuh 
was  the  first  to  perceive  that  here  was  the  means  of  obtaining  a 
steady  fall  of  pressure. 

Now  it  is  in  general  true,  that  every  turbine  makes  the  maxi- 
mum use  of  the  energy  supplied  to  it  only  at  one  particular  peripheral 
velocity  and  rate  of  steam  flow.  Schulz  has  accordingly  chosen  the 
number  of  expansion  sta.ges,  the  blading,  and  the  cross-section  of 
the  steam  passages  in  the  individual  turbines  to  suit  a  certain  mean 
speed  of  flow.  Since  the  elasticity  of  the  steam  has  also  to  be  con- 
sidered, the  loss  of  economy  is  very  slight,  even  if  the  rate  of  flow 
vary  within  small  limits.  The  number  of  auxiliary  turbines  neces- 
sary for  maximum  economy  during  manoeuvres  can  only  be  deter- 
mined by  experience. 

The  Schulz  turbine  works  at  every  speed  with  nearly  constant 
boiler  pressure.  If  its  speed  is  to  be  reduced,  the  number  of  the 
auxiliary  expansion  stages  is  increased  and  the  rate  of  flow  of  the 
steam  becomes  smaller,  because  the  latter  has  to  go  through  turbine? 


71 

with  passages  of  small  cross-section  before  it  passes  into  the  main 
turbine  on  its  way  to  the  condenser.  The  speed  of  the  turbine 
decreases  as  the  number  of  the  expansion  stages  is  increased,  and 
extravagance  in  fuel  is  thus  avoided. 

Now,  it  is  impossible  to  secure  an  absolutely  perfect  use  of 
steam  at  every  speed. 

If,  for  example,  the  main  turbine  be  so  designed  that  the 
steam  will ,  at  the  highest  output ,  already  have  reached  the  condenser 
pressure  at  its  exit  from  the  last  expansion  stage,  it  is  inevitable  that, 
when  all  the  auxiliary  turbines  are  used,  the  last  blade  rings  of  the 
main  turbine  should  rotate  without  performing  work. 

In  fact,  the  condenser  pressure  is  attained  before  the  steam 
leaves  the  main  turbine  ;  for  it  is  impossible  so  to  arrange  the  blading 
and  the  cross-sections  of  the  passages  that  all  requirements  are  satis- 
fied at  both  high  and  low  pressures.  If,  at  the  smallest  output  of  the 
plant,  the  last  few  expansion  grades  be  ineffective,  the  uselessly 
revolving  hindmost  blade  rings  waste  work  in  unnecessary  ventila- 
tion, and  the  amount  of  this  must  be  deducted  from  the  effective 
output  of  the  engine.  The  loss  is,  however,  small,  owing  to  the 
fact  that  the  condenser  pressure  is  always  low,  and  it  also  becomes 
less  as  the  rate  of  steam  consumption  diminishes. 


We  have  shown  that  the  Schulz  turbine  system  possesses  the 
following  essential  advantages  for  marine  use  : — 

1.  The  maximum  of  economy  at  all  speeds. 

2.  High  pressure  of  the  steam  on  its  entrance  into  the  tur- 
bine at  every  speed. 


72 

3.  Powerful  and  prompt  action  in  reversing. 

4.  The  regulation  of  the  end  thrust  exerted  on  the  shaft  by 
the  steam  and  by  the  propeller  respectively. 

5.  The  combination  of  action  and  reaction  turbines  in  one 
system. 

6.  The  division  of  the  whole  plant  into  several  detachable 
portions,  so  that  a  steady  expansion  of  the  steam  is  always  attained. 

7.  The  simple  and  convenient  arrangement  of  the  various 
valves. 

8.  An  even  distribution  of  the  work  over  the  different  shafts. 

9.  Economy  in  space  and  weight  in  comparison  with  other 
systems  (Figs.  39  to  43.). 


In  Figs.  39  to  43  a  comparison  is  made  between  the  space  re- 
quirements of  the  best  known  turbine  systems.  The  diagrams  show 
the  plans  and  elevations  of  these  turbines  on  a  scale  of  1  to  100.  The 
outputs  range  approximately  from  500  to  600  horse-power — in  the 
cases  of  Curtis'  turbine  and  Schulz*  reaction  turbine  from  500  to 
800  horse-power.  The  speeds  of  revolution  are  from  2,000  to  3,000  per 
minute.  This  comparison  shows  that  the  Schulz  turbine  econo- 
mizes space  to  a  considerably  greater  degree  than  do  those  of  the 
other  systems. 

The  patent  specifications  bear  reference  to  the  further 
development  of  the  action  turbines,  as  well  as  of 
the  reaction  turbines  on  the  Schulz  system  and  to  the  distribution  of 
the  turbines,  in  a  compound  engine,  over  several  shafts. 


73 

In  this,  special  attention  is  paid  to  the  simplicity  and  con- 
venience of  the  levers  which  control  the  cutting  off  of  the  various 
auxiliary  turbines  during  manoauvres. 

Unlike  many  other  inventions  on  the  domain  of  steam  tur- 
bines, the  Schulz  system  has  a  firm  foundation  in  the  extensive 
practical  experience  of  its  designer.  It  is  to  be  greatly  desired  that 
these  turbines  be  soon  brought  into  competition  with  those  of  other 
types  ;  their  success  will  then  not  be  long  delayed. 


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